Fashion resale, regardless of platform, is always an exercise in frustration. Few things will sell for anywhere near what you originally paid for them, even if they are in brand new condition, and even if they do, by the time TRR/eBay/Poshmark/whomever takes their cut you'll make only a handful of dollars. There is a lot of consignment/resale out there and EVERYONE wants a deal.
If you think TRR is bad, try Poshmark. Just take for instance a beautiful pair of designer suede boots that I've had up for months, in near-new condition. I'm asking a quarter of what I paid for them, have tons of saves, and I regularly get offers for 20 bucks.
I think the benefit, as jenlee above points out, is that as a buyer it keeps these items out of the landfill, is a great way to recycle/reuse, and a great way to score quality items at a discount. As a seller, though, unless you have a closet full of in demand luxury items that you need to liquidate, the most you'll do is stockpile a bit of extra cash over the long run to put toward a few new things.